Water-insoluble microparticles having a diameter of a dozen or so micrometers to 0.5 μm can be used to extract/purify, separate, and recover a target component by allowing the surface of the microparticles to have various chemical affinities. Further, such microparticles can also be used to recover target cells by allowing them to identify a specific cell-surface molecule. Therefore, microparticles having a functional molecule introduced onto their surface depending on the type of target are commercially available. Among these microparticles, those made of a ferromagnetic material such as iron oxide allow a target component to be recovered by a magnet without the need of centrifugation, and are therefore advantageous for automation of chemical extraction/purification.
For example, a system is commercially available, which performs a series of processes from extraction of nucleic acid from cells to analysis by gene amplification reaction in a single device. For example, GeneXpert System available from Cepheid (USA) can perform a series of processes from nucleic acid extraction to analysis by gene amplification reaction in a single cartridge-type device and can treat simultaneously up to 16 samples (the technical contents of GeneXpert System are described in Non-Patent Document 1). Further, for example, Simplexa (Non-Patent Document 2) available from 3M can perform a series of processes from nucleic acid extraction to PCR in a single disk-shaped device in which 12 samples can be immobilized.
On the other hand, magnetic particles are commercially available as one of reagents supplied as an extraction/purification kit. Such a kit includes two or more reagents contained in separate containers, and when the kit is used, each of the reagents is dealt and dispensed by a user with a pipette or the like. Even in the case of a currently commercially available automated device, dispensing of liquid is performed by mechanically operating a pipette. For example, a system (Non-Patent Document 3) is commercially available from Precision System Science Co. Ltd., which uses magnetic particles to extract nucleic acid.